This invention relates, in general, to optical devices and, more particularly, to fabrication of molded waveguides and their use.
At the present time, optical waveguides, photonic devices, land standard electronic components are not effectively integrated for several reasons, such as difficulty in manufacture, difficulty in assembly, and the like. For example, fabrication of optical waveguides is achieved by either a polymer spin-on technique or a diffusion technique, both of which require expensive lithography steps. Further, both fabrication techniques provide a planar waveguide structure that does not easily enable light signals that are perpendicular to the planar structure to couple into the waveguide, thus not enabling some photonic devices to be utilized easily with planar waveguides. Moreover, both fabrication techniques are ineffective and inefficient for manufacturing waveguides in high volumes for several reasons, such as complex processing steps, difficulties in controlling the processing steps, and the high cost of doing these processing steps.
Briefly, as practiced by one method in the prior art, a polymeric film is spun on a substrate. A portion of the polymeric film is subsequently exposed to light by a photolithographic process, thereby changing the refractive index of the polymeric film and creating a waveguide in the polymeric film. However, subsequent multi-step processing for making the waveguide useful, such as removal of the polymeric film from the substrate, lamination processing, curing processing, and other processes typically are required for the waveguide to be useful. Additionally, it should be pointed out that use of this method for manufacturing waveguides does not lend itself for coupling light signals that are perpendicular to the waveguide. Further, it should be noted that each additional processing step incurs an additional cost, as well as presenting an opportunity to induce defects into the waveguide.
Alternatively, in another method practiced in the prior art, a layer such as a glass is applied to a substrate. The layer is patterned by a complicated lithographic process, thereby producing portions that are masked and portions that are open or clear. Typically, ions are subsequently diffused into the open portion of the layer, thus changing the refractive index of the layer and making a waveguide. However, by using the photolithography process, a high cost is incurred into manufacture of the waveguide. Once again, the waveguide fabricated by this method does not have any provisions for enabling light signals that are perpendicular to the waveguide to be coupled to the waveguide. Additionally, use of this particular method for manufacturing waveguides incurs a high cost of manufacture for several reasons, such complexity of processing steps, number of processing steps, and the like.
It can be readily seen that conventional methods for making waveguide have severe limitations, while not readily enabling light signals that are perpendicular to the waveguide to be coupled. Also, it is evident that conventional processing uses a multitude of steps which are complex and expensive, thereby making the manufacture of conventional waveguides expensive. Therefore, a method for making a waveguide that enables light signals that is perpendicular to the waveguide to be coupled would be highly desirable.